Publisher Health

Receiving a tiny monetary reward at the right moment could play an outsize role in motivating us to exercise, according to a large-scale and innovative new study of how to nudge people to show up at the gym.

The study, published today in Nature, involved 61,293 American gym members, 30 prominent scientists working at 15 universities, and more than 50 different motivational programs. In addition to reward points, incentives ranged from a free audiobook for gym use to cheery instructions from researchers to reframe exercise as fun. While some of the programs galvanized additional gym visits, others, including some the scientists had absolutely expected to inspire more exercise, did not.

The study’s findings, positive and the reverse, offer timely insights into how the rest of us might better motivate ourselves to keep our upcoming New Year’s exercise resolutions. But just as important, the study, in its ambition, scope and structure, is meant to serve as a road map for future investigations into the mysteries of human behavior and why so many of us act as we do and sometimes, despite our best intentions, keep skipping that next spin class.

The science of human behavior, including whether and why we exercise, can be squishy and rife with research hurdles. Many past studies have looked at how to build habits, for instance, or instill confidence or stick to an exercise routine. But the vast majority of those studies have been small-scale or homogeneous, recruiting only affluent, well-educated white people, for example, or healthy, young college students, or only men or only women.

Those studies have also used a wide range of methods to track behavior change, making it difficult to compare data from one study to another. In addition, many have relied on subjective measures, such as asking people how they feel during and after a study, a topic on which we can be, intentionally or not, untrustworthy. The result has been a replication crisis in behavior science, with researchers unable to repeat the findings of many past studies, calling the original results into question.

These issues naturally concerned Katy Milkman, a professor at the Wharton School of the University of Pennsylvania and author of the 2021 book “How to Change” (one of Well’s favorite health books of the year) and her colleague Angela Duckworth, also a professor at Wharton and author of the 2016 best seller “Grit.” Among the foremost behavioral scientists at work today, they were convinced their field could and should become more scientifically rigorous, which led them to begin noodling with the notion of megastudies.

A megastudy, as they defined the concept, would be large in scale, involving thousands of participants, and not the dozens commonly used in behavioral research. It would also randomly expose large groups of volunteers to a range of behavior modifications or other interventions, employing objective measures to assess whether an intervention had actually worked.

These ideas brought the research team to the 24 Hour Fitness chain. Already, they had decided that one of their first megastudies would concentrate on exercise behavior, in part because it is easy to measure increases or declines in workouts and visits to the gym, but also because encouraging people to exercise more can alter lives by boosting health.

With its nationwide network of hundreds of gyms, 24 Hour Fitness offered the researchers millions of potential participants for their massive study. Then they invited dozens of other scientists to come up with interventions they felt would up people’s willingness to work out. They also created an umbrella program, called “Step Up,” which gym members could choose to join, earning Amazon reward points worth about $1.00 once they did. The “Step Up” program promised to provide them with new ways to motivate themselves to work out.

More than 61,000 members joined the “Step Up” program, after which the scientists divided them into 53 groups. One group, which served as a control, changed nothing about their lives or gym time. The others were then assigned to receive a basic package of motivational help that included advice to plan the exact day and time of each workout, a texted reminder from the research team about those plans, and a minuscule reward if they did work out, worth about 22 cents in reward points. These kinds of efforts can be key to increasing motivation, the researchers felt, and would serve as a baseline test of whether the study was inspiring people to exercise more.

On top of this basic package of reminder texts and small rewards, the researchers then randomly assigned the gym members who were not in the control group to one of 52 different motivational programs developed by the researchers. In one, for example, the members earned reward points worth about $1.75 every time they visited the gym; in others, they shared their workouts with friends on social media, signed a fitness pledge to show up regularly or agreed to reflect after each workout on how it had affected them. Each group included at least 455 participants. Each intervention lasted a month.

Before and during that month, the researchers tracked how often people turned up at their gym. They also asked outside exercise and behavior experts which interventions they expected would be most successful.

The results surprised almost everyone. Dr. Duckworth, for one, told me she had thought encouraging people to view workouts as fun would get them to the gym more often, but that group showed only a minuscule increase in gym visits. (Almost everyone in the intervention groups worked out a bit more often than the people in the control group.)

The most successful intervention, though, turned out to be giving people the equivalent of 9 cents’ worth of reward points if they returned to the gym after missing a planned workout. That program increased gym visits by about 16 percent, compared to the baseline package of planning and text reminders. Almost as effective was simply giving people a bigger reward, worth $1.75, every time they worked out. It increased exercise by about 14 percent, compared to the baseline package.

Over all, the findings suggest that if we want to exercise regularly in 2022, we should, in general:

• Plan a reasonable workout schedule;

• Program reminders of that schedule into our phone or with an admonitory spouse or training buddy; and

• Find small ways to reward ourselves when we exercise as planned. Drop a dollar into a bowl for every workout, for instance, and let the proceeds mount.

Perhaps most important, though, the study’s results show, we should “try not to miss more than one workout,” Dr. Milkman said. Getting ourselves back to the gym or pool or walking trail or cycling path after skipping one session might have special potency in helping us show up for the next workout, and the next after that.

Of course, this study, large and complex as it is, involved only people interested enough in fitness to join a gym, so the results may not apply to everyone else. The interventions also lasted only a month, which could be too short to see behaviors change. Dr. Duckworth and Dr. Milkman, who now co-direct the Behavior Change for Good Initiative at Wharton, are planning other megastudies, related not only to encouraging exercise, but also other major health issues, such as vaccination hesitancy.